Vauxhall Corsa 1.2 - always damp under driver's side.

For the past few months I have noticed that my Vauxhall Corsa ('01 reg) is damp under foot on the driver's side. The mat and floor are constantly wet and it is making alot of condensation in the mornings when it is cold. I have taken it to the garage twice...once at my local garage and then the other being a Vauxhall garage. Neither could find any major leak but Vauxhall said the next step would be to pull out all the seats and look that way. I cannot afford this but I am wanting to find out where the leak is coming from, as it must be small. Any help would be very much appreciated :)

A few things can cause this, has the windscreen been replaced? are you door seals split? check under the bonnet in the direction of the windscreen, there are 2 wells, these can get blocked by leaves in-turn blocking the water outlets ( A small tube) Under the carpet/mats there are Plugs in the floor/body of the car, these were there when the car was manufactured, have a look under the car in the area of the drivers side, has it a roof aerial? Is it tight? is the black seal around the base of the aerial intact? check the back of the car under the bench seat is it dry? Is the floor dry? look in the boot is it wet? rear door seal or wiper seal U/S. A lot of Qs that how you find the answer.